CVE-2026-22809 is a vulnerability categorized under CWE-1333, which involves inefficient regular expression complexity leading to a Regular Expression Denial of Service (ReDoS) condition in the tarteaucitron.js library. Tarteaucitron.js is a JavaScript library widely used for managing cookie consent banners in compliance with privacy regulations such as GDPR. The vulnerability specifically affects versions prior to 1.29.0 and is triggered by the handling of the issuu_id parameter. The underlying issue is that the regular expression used to validate or process this parameter exhibits excessive backtracking or complexity, allowing an attacker to craft input that causes the regex engine to consume disproportionate CPU resources. This results in a denial of service by slowing down or halting the execution of the script, impacting the availability of the cookie banner functionality and potentially the broader web application relying on it. The CVSS 3.1 score of 4.4 indicates a medium severity, with the attack vector being local (AV:L), requiring low complexity (AC:L), high privileges (PR:H), no user interaction (UI:N), and impacting availability only (A:H). No known exploits are currently in the wild. The vulnerability was published on January 13, 2026, and fixed in version 1.29.0 of tarteaucitron.js. Since tarteaucitron.js is commonly integrated into websites to ensure cookie consent compliance, exploitation could degrade user experience or cause service interruptions, especially on high-traffic sites.

For European organizations, the impact of this vulnerability primarily concerns service availability. Since tarteaucitron.js is used to manage cookie consent banners, exploitation could lead to denial of service conditions that disrupt the display or functionality of these banners. This disruption could result in non-compliance with GDPR and other privacy regulations, potentially leading to regulatory scrutiny or fines. Additionally, degraded user experience on websites may affect customer trust and engagement. The requirement for high privileges and local access limits the attack surface, reducing the likelihood of widespread exploitation. However, organizations with complex web infrastructures or those that allow internal users or processes to manipulate the issuu_id parameter could be at risk. The vulnerability does not affect confidentiality or integrity, so data breaches or unauthorized data modification are not direct concerns. Nonetheless, availability issues can indirectly impact business operations and compliance posture.

To mitigate this vulnerability, European organizations should immediately upgrade tarteaucitron.js to version 1.29.0 or later, where the inefficient regular expression handling has been corrected. Web development and security teams should audit their web applications to identify any use of vulnerable tarteaucitron.js versions and prioritize patching. Additionally, organizations should implement monitoring for unusual CPU usage or performance degradation on web servers hosting affected applications, which could indicate attempted exploitation. Restricting access to interfaces or parameters that accept the issuu_id input to trusted users or systems can further reduce risk. Employing web application firewalls (WAFs) with rules to detect and block suspicious input patterns targeting regular expression vulnerabilities may provide additional protection. Finally, maintaining an inventory of third-party libraries and ensuring timely updates is critical to prevent similar issues.